Isn't the reason Romance of the Three Kingdoms is so popular because the characters are so charming?

Even if you look at the Chu-Han Contention, there are two protagonists, Liu Bang and Xiang Yu, but both have severe personality flaws, which makes it a bit difficult to connect with them.
Liu Bang abandoned his own child from a carriage, was manipulated by his wife after being deceived, and even turned his subordinates into salted fish...
Xiang Yu buried surrendered soldiers alive, killed the emperor, and his refusal to listen to Fan Zeng was frustrating to watch...
On the other hand, the protagonists of the Three Kingdoms, Liu Bei and Cao Cao, are less like that.
In the Romance, Liu Bei is portrayed as so kind that it's frustrating, and Cao Cao is portrayed as cruel yet brilliant, creating a clear dynamic, while still showing unexpected charms from time to time...
In the end, neither of them unified the world, but the story keeps you immersed by focusing on the subsequent rivalry between Zhuge Liang and Sima Yi...
Zhuge Liang and Jiang Wei also die tragic deaths,
and Cao Cao's descendants eventually become mere puppets... On top of that, they are killed off openly, making the tragic endings for both protagonists, Liu Bei and Cao Cao, truly compelling...
I think it was popular because the period spans about 70 years with a good number of characters, and the figures chosen as protagonists are genuinely charming.
The Spring and Autumn period is too long,
the Chu-Han Contention focuses too heavily on Han Xin and Xiang Yu,
and during the Sixteen Kingdoms period, it's hard to distinguish the figures due to the internal strife of the Sima clan, and they die off too quickly, which makes it less interesting...